In high voltage power transmission systems there is a lot of various types of communication provided between devices such as control and/or protection computers and control and measurement nodes. A control and measurement node here typically may interface various units such as breakers, disconnectors, grounding switches and load tap changers in transformers. They also typically perform measurements.
The data sent in such communication might here include measurement samples taken in the process being controlled, which are here normally current and voltage samples in various sections of the system, field bus type of data such as commands, alarms and indications, time synchronization signals for synchronizing the operation of elements with which such control and measurement nodes interface as well as sampling synchronization signals for synchronizing the time samples which are to be taken by a control and measurement node.
Traditionally the communication for these various types of data have been provided using different types of connections. Field bus type of data is here normally sent on a field bus connected between a computer and a number of control and measurement nodes, measurement samples are often sent on a TDM (Time Division Multiplex) bus or direct point-to-point connections, time synchronization data is often sent on dedicated point-to-point connections, while sample synchronization signals are often sent on dedicated point-to-point connections.
This means that there are a great number of various types of connections between devices such as a computer and a control and measurement node.
It would therefore be of interest if these connections could be reduced.
EP 1 191 732 describes a material processing data communication system and method for communicating data between internal assemblies of the system. Here clock data is encoded in data sent on a fiber optic link provided between two interconnected data ports of two internal assemblies. The clock data is encoded onto the data using 8B/10B (8 bit/10 bit) coding and is used for reconstructing this data. Also CRC (Cyclic Redundancy Code) coding is described.
US 2005/0089334 describes an optical system where management messages are superposed onto data transmitted at high frequency via an optical fiber.
US 2005/0135421 describes Ethernet data frames in a device-to-device interconnection, where 8B/10B coding has been used. Through the 8B/10B coding control messages are interleaved with content data.
However, none of these documents concerns a high voltage power transmission system.
In view of what has been described above there is therefore a need for reducing the number of connections between a first and a second device in a high voltage power transmission system.